m20b23 rev issues

Post Mon Jul 04, 2011 10:33 am

Hi so i have a pfl coupe 323i uk import to New Zealand have only owned the car for about 7-8weeks and it was going fine using it as a daily until one day after work it wouldn't start, it wouldn't crank so we start it with a screwdriver bridged the termials on the starter. The next day i went to start it and the starter was just spinning so i took another car to work and left my car for 5days.

I push started it and got it going it felt weird tho i thought it was just cold so i took it for a drive up the road to warm it up and around 1km up the road it was having issues reving and idling, in neutral it was reving itself up to 5k+ then stalling and in gear it wouldn't rev pass 1.5k. So i checked the AFM the flap wasn't stuck open or closed it was free to open/close, i noticed the ICV pipe wasn't connected to the manifold so thats now all good.

Next day i took it for a little drive again was told to rev it to 3k for about a min, while it was cold it reved fine up to red line then back to idle took it for a drive again then about 1km up the road it went dead wouldn't rev pass 1k in neutral or gear sounded like it wasn't running on all 6 like it was misfiring also one of the exhaust pipes at the rear had black smoke out of it and the other pipe was fine. I pulled the plugs out and they were all black (i do not know when the spark plugs or HT leads were last replaced) The HT leads look worn one of the wires came off the plug end when i touched it and the wire was twisted like somebody has tired to fix it, The rotor and cap looked fine no cracks or anything, oil looked fine no milkshakes.

Atm i don't really know what could cause this or what is going on i was going replace the spark plugs and HT leads and see what happens as the engine has fuel otherwise it wouldn't be blowing black right? so must have something to do with spark, I've got a starter motor on the way so i can check things while its cranking, any help would be great

Post Mon Jul 11, 2011 6:41 am

so ive replaced the starter motor, HT leads and spark plugs. I can hear it misfiring a little bit at idle but nothing really i think it just needs a little tune up with a timing light.

Ok so the engine starts fine, idles fine, revs in neutral no issues i did notice after a few mins of running the car it had smoke coming from the exhaust manifold have been told it was leaking a little bit but i didn't notice it as it wasn't this bad, i took it for a drive once out of the driveway i tried going pass 2k rpm it just lost power it feels like the spark is too weak it doesn't feel like a rev limiter.

I started it today and it reved fine while cold and in neutral i didn't push it higher then 4k, however i only ran the car for a short time and still want to know what caused this and if its going to happen again, Im wondering if it has a blocked cat and once ran for awhile it builds up enough pressure to block exhaust gases and slow rpm.

Post Wed Jul 13, 2011 4:11 am

Sounds like this but only once warm i think it might be pre-ignition

starts to sound like a rotary and wont rev past 1.5k-2k ish, I've tried removing the AFM and the car runs so rich and is alot worse, Going to do a cylinder pressure test and a Fuel pressure check

Post Wed Jul 13, 2011 7:38 pm

the car in the clip sounds like its got no oil in it.

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im only replying to your thread as no one else has. the problem could be so many things its just a case of you going through everything systematicly. sounds like your doing that anyway. three basics are compression, spark and fuel. you def got spark and fuel if it runs but check fuel pressure, clean injectors. are you still bump starting??? is your battery good?

Post Thu Jul 14, 2011 11:00 am

Battery is good replaced starter motor, I added injector cleaner to my fuel hasn't seemed to help i think its the fuel pressure, when cold the cold start injector just gives it enough fuel to run and rev and when it warms up its starving it

Post Thu Jul 21, 2011 7:25 am

well found the prob the yellow/black wire on the starter motor wasn't connected, Why would it effect running issues? shouldn't it just effect cracking? well no because its connected to the injector harness so it was leaning out the engine. Still puffing white smoke and black sot, most likely due to over a month of not driving and water in fuel, dry compress test 1 - 185 psi, 2 - 190 psi, 3 - 185 psi, 4 - 191 psi, 5 - 182 psi, 6 - 179psi so that seems fine. Silly aye?

Post Thu Jul 21, 2011 11:50 am

There's not a lot of knowledge available for the early versions,I'm afraid,plus this being in the engine conversions section means that it does not attract enough attention.

I'm wondering if this is the cold start system staying on and causing overfueling?

Your compression fiqures are good and even,your mention of the injector harness shows that you are looking for problems in all the right places,we often find corroded wires under the rubber boots on this connector.

Welcome to the zone,BTW!